Method of electroplating nickel and cobalt, baths and agents therefor



' control and supervision.

Patented Oct. 8, 1946 METHOD OF ELECTROPLATING NICKEL AND COBALT, BATHS AND AGENTS THEREFOR Meyer L. Freed, Ansonla, Conn., asslgnor to The Seymour Manufacturing Co., Seymour, Conn.

No Drawing. Application April 28, 1939, Serial No. 270,513

34 Claims. 1

This invention is concerned with addition agents for use in the electrodeposition of nickel groupmetals, such as nickel and cobalt, with electroplating baths containing the addition agents and with the process of electrodeposition carried out in solutions containing the addition agents.

While the invention is generally applicable to the electrodepositionof nickel group metals, such as nickel and cobalt, its immediate important applicability is in the electrodeposition of nickel. Therefore, for convenience the invention may be illustrated by its use in nickel plating, although it is not to be restricted thereto.

The recent trend toward developments for the direct deposition of the so-called bright nickel has shown some progress in the desired direction. However, among the various agents tried in attempting to reach the end sought, each has exhibited some undesirable shortcoming to restrict its general application.

The weakness of some of the agents is the limited operating conditions under which they may be employed, requiring very close and expensive Others do not actually produce a satisfactorily finished bright surface, which may, for example, be subjected to a succeeding deposit of another metal without intermediate treatment to prepare the first deposited surface to takeon the subsequently deposited plate. Still others are too fleeting in their activ-- ity in the plating bath and too hard to follow during the plating operation by practical analytical methods, thereby presenting difiiculties in their use insurmountable to commercial application. Other examples require the use of still other agents simultaneously in the bath to pre-- vent pitting; Many of them, in addition, require agitation to yield even, their limitly available results.

The present invention provides for the preparation of a nickel plating bath free of the shortcomings characteristic of the earlier addition agents and permitting the operation of an easily controlled process of electrodeposition yielding a carried out with minimum supervision and analytical control over an extensive period, within a broad range of hydrogen ion concentrations and under current densities suitable to a wide variety of shop needs to consistently yield an evenly ductile nickel deposit on even the most intricately formed surfaces, and possessing admirable adhesion even on steel.

Broadly described, ortho-sulfobenzaldehyde is a. sulfonated aromatic aldehyde. Other addition agents capable of exhibiting the difierent properties in varying degrees are thus generically referred to as sulfonated aromatic aldehydes, which may be monoor poly-sulfonated, such as the su1- lonated aryl aldehydes, which may be polynuclear, as exemplified by the sulfonated naphthaldehydes or sulionated anthraldehydes. Particularly desirable are the mononuclear aryl derivatives', illustrated by sulfonated cinnamaldehyde, exemplifying the unsaturated alkyl, or vinyl derivatives, and sulfonated salicylaldehyde and other sulfonated benzaldehydes, including the saturated alkylated compounds, such as tolualdehyde, or especially the non-alkylated compounds as ortho-suliobenzaldehyde, or the alkoxylated derivative as in sulfonated paramethoxy benzaldehyde (anisaldehyde). The nickel salt or 2.5 disulfobenzaldehyde illustrates the polysulfonated form.

The various types of the addition agent may be employed either as the free sulfonic acid derivative of the aldehyde or as a salt thereof.

brilliant, ductile nickel deposit over a wide range on the most intri- Thereiore the terms sulfonic acid," sulfonate," and sulfo-" employed herein and in the appending claims are each used in the generic sense as if each is represented as the radical SO3X in which X may be hydrogen or a salt forming cation such as a metal, for example, an alkali metal, as sodium or potassium, or an alkaline earth metal, as magnesium, or a nickel group metal, as nickel orcobalt, or other metal as cadmium, mercury, zinc and the like, or an amine type cation including ammonium and those derived from an amine or alkylamine as methylamine or ethylamine, or from an alkylolamine as mono-, di-, or triethanolamine, orother suitable salt iorming base. Distinctly effective as an addition agent is drthosuliobenzaldehyde, either in the form of the free sulfonic acid derivative or of any of the salts of any of the salt forming cations just above described.

The addition agents of this invention may be applied to any commonly employed nickel plating bath containing any of the. usual nickelplating effective range, for example, with orthosulfo-' benzaldehyde, is from about one-half A) gram to twenty (20) grams per liter, although under some operating conditions less than one-half gram and in others more than twenty grams per litr can be used.

An attractive feature of the process of the invention is the wide range of hydrogen ion concentration over which it is operable. larly unique in this respect is ortho-sulfobenzaldehyde which is eflective over a wide range from as little as around a pH of 1.5 to around 5.5, and admirably eifective at any point in the range of pH from about 2.0 to about 5.0, measured electrometricalLv. In fact, it is possible to permit the hydrogen ion concentration or the plating bath to vary over the duration of the plating operation of the bath at any point within the indicated zone. It is thus found that little control of hydrogen ion concentration is necessary over a long period of operation thereby eliminating to a large degree the necessity for close supervision and analysispf the bath during long extended operation with regard to this particular operating condition.

At the same time, as found with ortho-sulfobenzaldehyde, the current density may be selected to suit a wide variety of shop needs for the electroplating bath may be operated at a current density of from about or less to around 75 or more amperes per cathode square foot, and even up to about 100.

Along with the just described operating conditions possible by the process of electrodeposition with the electroplating baths of the invention, an unusual throwing power is observed. 'This characteristic makes agitation unnecessary in the operation of the plating bath, although agitation may be employed if desired. It has thus been Example 1 Ounces for gallon Nickel sulfate (6H20) 37 Nickel chloride (6H20) 8 Boric acid 5 Ortho-suliobenzaldehyde The electroplating bath can be operated at a temperature of from about 100 F. or less to about 140 F. or more, but a good operating range is be tween 110 and 120 F.

The concentration of the plating salts in the bath of the example may be varied to include the following ranges, although more or less of each Particuof the primary constituents may be used,'if desired:

, Ounces per gallon Nickel sulfate (61120) 2B t050 Nickel chloride (6H2O) 3to 8 Boric a 2 to 5 "agent, such as ortho-sulfobenzaldehyde is presm ent in the plating bath, it is not necessary to It has also been found that when an addition employ in the bath an anti-pitting agent, i. e.

an agent that lowers the surface tension and avoids pitting.

Other organic addition agents are found to be applicable only within a limited range of hydrogen ion concentration and yield only a reasonably bright nickel deposit. It has been found that if part of the amount of such agent present is replaced by the addition agent of this invention exemplified by ortho-sulfobenzaldehyde, then the plating bath in which the combination of the two agents is present can be operated without the necessity of, adjusting thehydrogen ion concentration during the extent of the operation while the pH varies between about 2.0 and about 5.5. Such plating bath will then also brilliant nickel deposit.

Thus when ortho-sulfobenzaldehyde is added to a given bath ordinarily operated with a naphthalene sulfonate, e. g., a disulfonate, as a brightening agent, in a quantity ,to replace an equal quantity deducted from the customary charge of the naphthalene sulfonate, the bath may be operated over an extended period without the necessity of testing or adjusting the pH while this characteristic of the bath may change within the range from about2.0 to about 5.5 and agitation, otherwise required, may be omitted.

Articles plated by the method of this invention do not require re-activation if the plating operation has been interrupted and is to be resumed or when the plated article is tobe subjected to a subsequent deposit-of another metal, or the nickel plated article can be subject to a chromium plating, after it has been exposed to the air, without the application of the customary so-called light wipe.

The present invention, particularly as exemplifled by the use of ortho-sulfobenzaldehyde, in-

' cludes among its advantages over the use of other addition agents, the fact that it is not critical in its operation and yields a brilliant deposit of the nickel group metal, e. g. nickel or cobalt, as compared with solely a reasonably bright deposit obtainable by the use of the others, and furthermore yields such brilliant deposit at decreased cost because of the reduction in supervision and analytical control and the elimination of agitation and the need of an anti-pitting agent.

While the invention has been illustrated by description of specific embodiments of it, it is understood that many modifications, alterations and equivalents may be employed within the scope of the invention as covered by the appending claims.

I claim:

1. An aqueous, acid electroplating bath which comprises in the aqueous medium a, metal-ion yielding material consisting essentially of a mixture of the sulfate and of the chloride of one of the metals selected from the group consisting of nickel and cobalt, together with an amount of a sulfonated aryl aldehyde sufficient to permit a brilliant cathodic deposit of the metal to be obtained upon the passage of an electric current yield a from an anode comprising said metal through the bath to a cathode, under the operating conditions.

2. An aqueous, acid electroplating bath which comprises in the aqueous medium a metal-ion 'yielding material consisting essentially of a mixclaim 2, in which the'sulfonated aryl aldehyde is a sulfonated phenyl aldehyde.

4. An aqueous, acid electroplating bath which comprises in the aqueous medium a metal-ion yielding material consisting essentially of a mix ture of the sulfate and of the chloride of one of the metals selected from the group consisting of nickeland cobalt, together with an amount of ortho-sulfobenzaldehyde sufllcient to permit a brilliant cathodic deposit of the metal to be obtained upon the passage of an electric current from an anode comprising said metal through the bath to a cathode, under the operating conditions.

5. An aqueous, acid electroplating bath as in claim 1, in which the sulfonated aryl aldehyde is selected from the class consisting of sulfonated henyl, sulfonated naphthyl and sulionated anthryl aldehydes.

6. An aqueous, acid electroplating bath as in claim 2, which in addition to the sulionated aryl aldehyde contains a second aryl sulionate brightening agent which is free from the aldehyde group, the two organic agents being present in a combined quantity sufilcient to permit a brilliant deposit of the metal to be obtained.

7. An aqueous, acid electroplating bath as in claim 2, which in addition to the sulfonated aryl aldehyde contains as a second brightening agent a naphthalene sulfonate which is free of the aidehyde group, the two organic agents being present in a combined quantity sufllcient to permit a brilliant deposit of the metal to be obtained.

8. An aqueous, acid electroplating bath as in claim 2, which in addition to the sulfonated aryl aldehyde contains as a second brightening agent a naphthalene polysulfonate which is free of the aldehyde group, the two organic agents being present in a combined quantity sufilcient to permit a brilliant deposit of the metal to be obtained.

9. An aqueous, acid electroplating bath which comprises in the aqueous medium a metal-ion yielding material consisting essentially of a mixture of the sulfate and of the chloride of one of the metals selected from the group consisting of nickel and cobalt, together with an amount of ortho-sulfobenzaldehyde and of a naphthalene 'disulfonate, the two organic agents being present terial consisting essentially of a mixture of the sulfate and o! the chloride of said metal, in the presence of a mononuclear aryl aldehyde in an amount suflicient to permit a bright cathodic deposit of the metal to be obtained under the operating conditions having its benzen nucleus sulfonated.

11.- Theprocess as in claim 10, in which the sulfonated aryl aldehyde is a sulfonated phenyl aldehyde.

12. The process of depositing a bright electrodeposit of a metal selected from the group consisting of nickel and cobalt, which-process comprises passing an electric current from an anode comprising said metal to a cathode through an aqueous, acid electroplating bath comprising in .the aqueous medium a metal-ion yielding material consisting essentially of a mixture or the sulfate and of the chloride of said metal, in the presence of orthosulfobenzaldehyde in an amount sufficient to permit a bright cathodic deposit of the metal to be obtained under the operating conditions as the brightening agent.

13. The process as in claim 10, in which the sulfonated aryl aldehyde is polysulfonated.

14. The process as in claim 10, which is carried out in the presence of both the sulfonated aryl aldehyde and a sulfonated aryl brightening agent which is free of the aldehyde group.

15. The process of depositing a bright electrodeposit of a metal selected from the group consisting of nickel and cobalt, which process comprises passing anelectric current from an anode comprising said metal to a cathode through an aqueous, acid electroplating bath comprising in the aqueous medium a metal-ion yielding material consisting essentially of a mixture of the sulfate and of the chloride of said metal, in the presence of both a mononuclear aryl aldehyde having its benzene nucleus sulfonated and a naphthalene sulfonate in a combined quantity sufllcient to permit a bright deposit of the metal .to be obtained under the operating conditions.

16. The process as in claim 15, in which the naphthalene sulfonate is a polysulfonate.

17. The process as in claim 15, in which the sulfonated aryl aldehyde is a sulfonated phenyl aldehyde and the naphthalene sulfonate is a polysulfonate.

18. The process as in claim 15, in which the sulfonated aryl aldehyde is a sulfonated benzaldehyde and the naphthalene sulfonate is a disulfonate.

19. The process as in claim 15, in which the sulfonated aryl aldehyde is ortho-sulfobenzaldehyde and the naphthalene sulfonate is a naphthalene disulfonate.

'20. An aqueous, acid electroplating bath which comprises in the aqueous medium a nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, together with an amount of 'orthosulfobenzaldehyde suflicientto permit a brilliant cathodic deposit of the metal to be obtained upon the passage 01 an electric-current through the bath, under the operating conditions.

21. An aqueous, acid electroplating bath which comprises in the aqueous medium nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, to-

. gether with a sulfonated cinnamaldehyde as the sole addition agent capable of causing a brilliant cathodic deposit and in an amount sufllcient to permit a brilliant cathodic deposit of the metal to be obtained upon the passage at an electric current through the bath, under the operating conditions.

22. An aqueous, .acidelectroplating bath which sin. the aqueous medium a nickel ion gether. with an amount of a sulfonated benzaldehyd'es'umcient to permit a, brilliant cathodic deposit of nickel to be obtained upon the passage of anelectric' current from the anode-through the bath to the cathode, under the operating conditions.

23. An aqueous. acid electroplating bath as claimed in claim 2, in which the benzene nucleus in the aromatic aldehyde is monosulfonated.

24. An aqueous, acid electroplating bath as claimed in claim 2, in which the sulfonated aryl aldehyde is a monosulfonated phenyl aldehyde.

25. An aqueous, acid electroplating bath which comprises in the aqueous medium a nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, together with ortho-sulfobenzaldehyde as the sole addition agent for causing a brilliant cathodic deposit of the metal to be obtained upon the passage of an electric current through the bath, under the operating conditions.

26. The process of depositing, a'bright electro- I having its benzene nucleus sulfonated and a.

naphthalene disulfonate, said addition agent composition being capable, upon addition to an aqueous, acid nickel plating bath containing nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride,

of causing a substantially uniform luster and brilliant cathodic deposit of nickel to be obtained upon the passing of an electric current from the anode through said bath to the cathode when the benzene-nucleus-sulfonated mononuclear aryl aldehyde and the naphthalene disulfonate are present in the bath respectively in combined quantities sufilcient to permit a brilliant deposit of the nickel to be obtained under the operating conditions.

28. A nickel electroplating bath addition agent composition as claimed in claim 27, in which the benzene-nucleus-sulfonated, mononuclear aryl aldehyde is a sulfonated-phenyl aldehydic compound selected i'rom the sulfobenzaldehydes an sulfocinnamaldehydes.

' 29. A nickel electroplating both addition agent compositions-s claimed in claim 27, in which the benzene-nucleus-sulfonated, mononuclear aryl aldehyde is ortho-sulfobenzaldehyde.

30. A nickel electroplating bath addition agent composition as claimed in claim 2'7. in which the benzene-nucleus-suifonated, mononuclear aryl aldehyde is sulfonated cinnamaldehyde.

31. An aqueous, acid electroplating bath which comprises in the aqueous medium a nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, together with an amount of a sulfonated-phenyl aldehydic compound selected from sulfobenzaldehydes and sulfonated cinnamaldehyde present in quantity suiiicient to permit a -brilliant cathodic deposit of nickel .to be obtained upon passage of an electric current through the bath, under the operating conditions.

32. An aqueous, acid electroplating bath which comprises in the aqueous medium a nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, to

gether with an amount of a sulfonated aryl aldehyde sumcient to permit a brilliant cathodic deposit of nickel to be obtained upon the passage of an electric current from the anode through the bath to the cathode, under the operatingconditions.

33. An aqueous, acid electroplating bath which comprises in. the aqueous medium a nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, together with an amount of a sulfonated mononuclear aryl aldehyde sufficient to permit a brilliant cathodic deposit of nickel .to be obtained upon the passage of an electric current from the anode through the biath to the cathode, underthe operating condit ons.

34. An aqueous, acid electroplating bath which comprises in the aqueous medium a nickel ion yielding material consisting essentially of a mixture of nickel sulfate and nickel chloride, together with an amount of a sulfonated phenyl aldehyde suilicient to permit a brilliant cathodic I deposit of nickel to be obtained upon the passage of an electric current from the anode through the loilath to the cathode, under the operating condione.

' MEYER L. FREED. 

